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Mesoscale Patterns in the Floristic Composition of Forests in the Central Western Ghats of Karnataka, India

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ABSTRACT

We describe the mesoscale floristic patterns in the central Western Ghats of Karnataka, India, through combined analysis of woody species abundance and stand structure data from a network of ninety-six 1-ha sampling plots spread across 22,000 km2. A total of 61,906 individuals (≥10 cm gbh) comprising 400 plant species from 254 genera and 75 families were recorded. Euphorbiaceae, Rubiaceae, Lauraceae and Moraceae families constituted 23.5 percent of the total number of species encountered. The relative dominance of species was skewed with Poecilonueron indicum, Xylia xylocarpa, Terminalia tomentosa and Anogeissus latifolia being dominant in some plots. Correspondence analysis (CA) and a nonmetric multidimensional scaling (NMDS) of plots by species abundances data showed similar arching patterns, with significant correlation between the first axis of CA and NMDS (r=0.77). Hierarchical clustering of plot scores along the three first CA axes resulted in splitting the plots into five different categories that broadly reflect the major bioclimatic features of the region. A multiscale bootstrapping test indicated that categorization of the wettest (wet evergreen group 1 and 2) and driest (dry deciduous) groups were robust (P<0.05 with 1000 bootstraps), while the remaining two transitional groups were uncertain (P=0.12 and 0.26 for moist deciduous and semi-evergreen group, respectively). Principal component analysis revealed that plots with similar floristic composition can encompass contrastingly different physiognomic structures (canopy cover, canopy height and mean tree diameter) probably in relation to their levels of disturbance. Observed patterns in the floristic composition have been discussed in the light of the complex interaction between the bioclimatic and disturbance regimes that characterize the region.

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